1. Field of the Invention
The present invention relates to a torque fluctuation damper pulley for transmitting the rotation from an engine of a motor car or the like to accessories while damping fluctuation in the rotation.
2. Discussion of the Related Art
A part of the driving power from an engine of a motor car is transmitted from a pulley attached to a shaft end of a crankshaft through an endless belt to accessories such as alternator and water pump for example. The crankshaft is rotated with rotation change (torque fluctuation) of the engine, and a pulley used therefor is generally provided with a torque fluctuation damper for damping the torque fluctuation.
As pulleys with a torque fluctuation damper of this kind, there has been known damper pulleys described in Japanese Unexamined, Published Patent Application No. 2001-159448 and Japanese Patent No. 3155280 (hereafter referred to as Related Art 1 and Related Art 2 respectively). These damper pulleys take the configuration that an inertia mass is jointed with the circumference of a hub, which is attached to the shaft end of a crankshaft to rotate bodily therewith, through a first rubber-like elastic member and that the hub and a pulley member are jointed with each other through a second rubber-like elastic member. Thus, the rotation is transmitted to the pulley member with the first rubber-like elastic member damping the vibrations in rotation transmitted from the crankshaft to the hub and at the same time, with the second rubber-like elastic member damping the fluctuation in rotational torque transmitted from the crankshaft to the hub through the sharing deformation thereof in a torsional direction.
However, in either of the forgoing torque fluctuation damper pulleys described in Related Art 1 and Related Art 2, it is probable that the deterioration or the like of the second rubber-like elastic member (16, 24) arranged between the pulley member and the hub causes the pulley member to shift in the axial direction at the time of being in use. Thus, a thrust bearing (20, 50) has to be provided to position the pulley member in the axial direction. This gives rise to problems that the cost rises due to an increase in the number of component parts of the damper pulley, the complication in construction and an increase in assembling steps.